Luminescence is produced in certain organisms as a result of a luciferase-mediated oxidation reaction. Luminescence is produced by firefly luciferase and other enzymes when those enzymes are mixed with certain synthetic substrates.
Luciferases can also generate light via the oxidation of enzyme-specific substrates, e.g., luciferins. For firefly luciferase and all other beetle luciferases, light generation occurs in the presence of luciferin, magnesium ions, oxygen, and ATP. Luminescence, if any, can be measured using a luminometer or any suitable radiant energy-measuring device. A luminescence assay can be very rapid and sensitive.